Removal of C.I. Acid Orange 7 from aqueous solution by UV irradiation in the presence of ZnO nanopowder

• Published in: Journal of hazardous materials Vol. 143; no. 1; pp. 95 - 101
• Main Authors: Daneshvar, N., Rasoulifard, M.H., Khataee, A.R., Hosseinzadeh, F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 08.05.2007; Elsevier
• Subjects: Adsorption; Advanced oxidation processes; Applied sciences; Azo Compounds - chemistry; Benzenesulfonates - chemistry; C.I. Acid Orange 7; Chemical engineering; Electricity; Electricity consumption; Ethanol - chemistry; Exact sciences and technology; Hydrogen Peroxide - chemistry; Hydrogen-Ion Concentration; Industrial Waste; Kinetic model; Nanoparticles - chemistry; Photolysis; Pollution; Reactors; Textile Industry; Ultraviolet Rays; Waste Disposal, Fluid - methods; Zinc Oxide - chemistry; Zinc oxide nanopowder; Advanced oxidation processes; Kinetic model; Zinc oxide nanopowder; C.I. Acid Orange 7; Electricity consumption; Energy consumption; Equilibrium constant; Surface reaction; Dyes; Hydrogen peroxide; Pollutant behavior; Color; Modeling; Powder; Ultraviolet radiation; Adsorption; Hydroxyl radicals; pH; Oxidation; Kinetics; Aqueous solution; Rate constant; Photochemical degradation
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2006.08.072

The removal of C.I. Acid Orange 7 (AO7) from aqueous solution under UV irradiation in the presence of ZnO nanopowder has been studied. The average crystallite size of ZnO powder was determined from XRD pattern using the Scherrer equation in the range of 33 nm. The experiments showed that ZnO nanopowder and UV light had a negligible effect when they were used on their own. The effects of some operational parameters such as pH, the amount of ZnO nanopowder and initial dye concentration were also examined. The photodegradation of AO7 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol, it was deducted that hydroxyl radicals played a significant role in the photodegradation of the dye. The kinetic of the removal of AO7 can be explained in terms of the Langmuir–Hinshelwood model. The values of the adsorption equilibrium constant, K AO7, and the kinetic rate constant of surface reaction, k c, were 0.354 (mg l −1) −1 and 1.99 mg l −1 min −1, respectively. The electrical energy consumption per order of magnitude for photocatalytic degradation of AO7 was lower in the UV/ZnO/H 2O 2 process than that in the UV/ZnO process. Accordingly, it could be stated that the complete removal of color, after selecting desired operational parameters could be achieved in a relatively short time, about 60 min.